Inside the cabin, you sit about 100mm higher than the driver of a big saloon, with all the visibility and feeling of security this brings. And it’s symmetrical, so you have panoramic vision on both sides. The sit-up driving position allows two passengers of normal proportions to sit closely but comfortably behind you, one on either side.

To get in, you press the button on the remote-locking key fob. The clamshell-shaped front half of the car’s glasshouse swings majestically forward on gas struts, a compelling piece of street theatre. When fully forward, a low-sided tub is revealed, dominated by the driver’s central seat. Simply step in and sit down.

When seated, you find your legs reach downwards to the pedals, and the steering wheel is two-thirds of a stretch away, framing an instrument pack that (but for its simplicity) recalls the cockpit architecture of a jet fighter.

Its modest but enthusiastic Smart engine (with special friction-reducing bore coatings for extra efficiency) produces 51bhp and flows with a non-Smart exhaust rasp to the rear wheels through a speeded-up, five-speed Smart-derived semi-auto gearbox, controlled by shift paddles but with a selectable auto mode for city crawling.

Turn the ignition key one click to the right, plant your clog on the central brake pedal, then thumb the starter button and the engine thrums into life. Press the button on the dash showing a forward arrow and you’ll select first (or the ‘A’ button if you prefer self-shifting mode), release the handbrake via a short lever by your right thigh, toe the accelerator gently and you’re away.

By the time you’ve travelled 20 yards, you’ll be reveling in the unique effects of light weight. This car weighs just 575kg, not much more than a big motorbike. It flows off the mark with an amazing lack of revs or effort. It may have a small engine, but there is absolutely no impression of it having to work hard to get you moving. The automatic clutch bites positively as you raise the revs and the car rolls willingly on its tall, skinny (not to mention affordable, light, soft-riding and space-saving) 145/70 tyres, mounted on light steel wheels.

By the time you’ve travelled 50 yards, you’ll have realized how easy it is to steer and position a car that is both very slim (not much more than half a normal car’s width) and exactly as wide to your right as it is to the left.

All-round visibility is terrific, but there’s another important benefit of the elevated driving position: whereas in a low and cramped car with this tiny footprint you might feel intimidated by London’s press-on cabbies and ferociously driven white vans, in the T25 you feel like their equal, far enough above the ground to be easily seen, high enough in your car to meet them eyeball to eyeball. What is more, you’re so much more agile than anything you meet that you can jink out of trouble with a blip of throttle and a flick of the wrists.

The outer edges of the prominent rear vision mirrors mark almost the exact boundaries of the car itself, but you can hardly believe it. For the first hour or so, you find yourself driving over little potholes and seams in the road, in order to judge exactly how close you can drive to obstacles. Even when you’ve got it, you can hardly believe it.

The T25 chassis has admirable grip and roll stiffness. Even chucked into 30mph roundabouts at 45mph, it grips brilliantly. There might be a whiff of stabilising understeer, but by the time you notice it, cornering forces are trying to lever you out of your elevated ‘chair’.